The realization space is
  [1   1   0   0   x1 - x3           x1 - x3   0    1                      x1 - x3    1    1]
  [0   1   1   1     x1*x2   x1*x2 + x1 - x3   0    0              x1*x2 + x1 - x3   x2   x2]
  [0   1   1   0         0           x1 - x3   1   x1   -x1^2*x2 + x1*x2 + x1 - x3   x1   x3]
in the multivariate polynomial ring in 3 variables over ZZ
within the vanishing set of the ideal
Ideal (x1^2*x2^2 - x1*x2^2 + x1*x2*x3 - x1*x2 + x1*x3 + x2*x3 - x3^2)
avoiding the zero loci of the polynomials
RingElem[x2, x1 - x3, x2 - 1, x3 - 1, x3, x1 + x2*x3 - x3, x1, x1*x2 - x1 - x2 + x3, x1^2*x2 - x1*x2 + x1*x3 + x2*x3 - x3^2, x1^2*x2 - x1*x2 + x1*x3 - x1 - x3^2 + x3, x1*x2 + x1 - x3, x1 - 1, x1 + x2 - x3, x1*x2*x3 - x1*x2 + x1*x3 + x2*x3 - x3^2, x2 - x3, x1^2*x2^2 + x1^2*x2 + x1^2 - x1*x2^2 - x1*x2 - x1*x3 + x2*x3, x1^2*x2 + x1^2 - x1*x2 - x1*x3 + x2*x3, x1^3 - x1^2*x2^2*x3 - 2*x1^2*x3 + x1*x2^2*x3 + x1*x2*x3 + x1*x3^2 - x2*x3^2, x1^2 - x1*x3 + x2*x3, x1^2*x2 - x1^2 + x1*x3 - x2*x3, x1 - x2, x1^2*x2 - x1*x2 - x1 + x3, x1*x2 - x1 + x3]